The technology of the present disclosure relates to an image forming apparatus.
In the related art, in an electrophotographic image forming apparatus, for example, image formation is performed by primarily transferring a toner image from a photoreceptor to a transfer surface of an intermediate transfer belt and then secondarily transferring the primarily transferred toner image to a sheet and the like. The image forming apparatus generally includes a cleaning device for removing toner remaining on the transfer surface after the secondary transfer.
The cleaning device has a rotary brush, a recovery roller, and a blade. The rotary brush sweeps off remaining toner on a surface of the intermediate transfer belt. The recovery roller receives a bias having a polarity opposite to that of toner, and electrically adsorbs and recovers the toner swept off by the rotary brush. The blade abuts a surface of the recovery roller and scrapes off the toner. The toner scraped off by the blade is conveyed to a recovery tank by a recovery screw.
In this type of cleaning device, there are cases where a pre-cleaning brush is provided at an upstream side in a belt rotation direction from the cleaning device. The pre-cleaning brush physically scratches toner attached to the intermediate transfer belt, thereby allowing the rotary brush to easily sweep off the toner. Furthermore, the pre-cleaning brush adjusts the polarity of the toner having passed through the brush to a predetermined polarity such that the toner is well electrically adsorbed by the rotary brush. In order to achieve the electrical operation, a bias having a predetermined polarity is applied to the pre-cleaning brush in advance.